Pumps



y 12, 1955 R. LUHMANN ETAL 3,260,215

PUMPS Filed May 20, 1964 2 sheets-sheet 1 Hg. I

y 12, 1966 R. LUHMANN ETAL 3,260,215 I PUMPS 2 Sheets-Sheet 2 Filed May20, 1964 .70 van/0r:

United States Patent 3,260,215 PUMPS Reinhold Liihmanu, Walter Hagemann,and Heinz Kath, all of Itzehoe-Tegelhorn, Germany, assignors to Siemen &Hinseh m.b.H., Holstein, Germany Filed May 20, 1964, Ser. No. 368,777 2Claims. (Cl. 103-96) This invent-ion relates to a self-priming sidechannel centrifugal pump with more or less axial flow towards thesuction slot. It aims at improving the air suction capacity of thispump.

For air suction or gas pumping respectively a side channel centrifugalpump makes use of a quantity of liquid which is retained in the pumpcasing by suitable means after the pump is shut oif.

To renew operation this liquid must be guided into the stage designedfor priming and must be retained in sufiicient quantity in the pumpingchamber during the whole priming period.

It is known that liquid is entrained and escapes out of said stageduring the gas pumping process through the pressure slot, and specialbafile plates and deflecting ribs have been provided in the pressurechamber to stow up this liquid in the side channel and to guide it backinto said stage. Nevertheless the air suction capacity of this pump isstill limited, since, as it has proved, during the gas pumping processliquid is also hurled through the suction slot back into the suctionchamber and into the suction pipe and is thus lost for the pumping ofthe gas, with a worsening effect on the air suction capacity.

According to the invention there is provided a selfpriming side channelcentrifugal pump with more or less axial flow towards the suction slotand a covering element provided in front of the suction slot,characterised in that the covering element, forming a guide rib, in therotational direction of the impeller wheel only covers the front part ofthe suction slot.

The purpose of this rib is to deflect liquid emerging from the impellercells at the beginning of the suction slot during the gas pumpingprocess and to guide it directly back to the impeller cells.

This obviously results in an essential improvement of the gas pumpingcapacity.

According to the invention it is further suggested to incline said ribtowards the impeller wheel, seen in the direction of rotation (of theimpeller wheel) and extend it quite close to it. This construction hasbeen found particularly favourable.

A specific embodiment of the invention will now be described by way ofexample with reference to the accompanying drawings, in which:

FIGURE 1 is a longitudinal vertical sectional view, partly diagrammatic,taken on line 1-1 of FIGURE 2 through a pump built in accordance withinvention.

FIGURE 2 is a transverse cross-sectional view taken on line 2-2 ofFIGURE 1, and

FIGURE 3 is a detailed fragmentary sectional view taken on line 3-3 ofFIGURE 2.

Referring more particularly to the drawings, on a shaft 1 is mounted animpeller wheel 2' which rotates in a casing formed by the casingcomponents 3, 4 and 5.

The inflowin-g pumping medium flows through the suction branch 6 intothe suction chamber 7 and there- 3,260,215 Patented July 12, 1966 afterthrough the suction slot 8 into the pumping chamber of the pump formedby the cells of the impeller Wheel 2 and the side channel 9.

According to the invention a guide rib 10 is provided in front of thesuction slot and forms a pocket which deflects the liquid emerging fromthe impeller cells during the air suction process, and then guides itback again to the impeller wheel. The position of the guide rib is shownmore particularly in FIGURE 3. It covers, in the example shown, only thestarting or upstream edge 12 of the suction slot and, is furthermoreinclined towards the impeller wheel, seen in the direction of rotationof the impeller wheel (indicated by the arrow in FIG. 3) and extendsquite close to the leading edges 13 of the radial blades 14 of theimpeller wheel 2.

The packing 11 has the duty of sealing the shaft passing through thepump casing.

While the above specification sets forth the invention with reference toa specific embodiment, it will be understood by those skilled in the artthat many modifications may be made without departing from the spiritand scope of the invention.

What is claimed is:

1. A self-priming side channel centrifugal pump comprising:

(a) a casing defining a suction chamber and an impeller chamber;

(b) a shaft journalled for rotation in the casing;

(c) an impeller wheel fixed on said shaft and disposed in the impellerchamber for rotation therein and having radial blades;

(d) a partition in said casing and separating said suction chamber andsaid impeller chamber;

(e) said blades being radially disposed in said impeller chamber andhaving radial leading edges facing said suction chamber;

(f) said partition being provided with a suction slot communicating saidchambers, said slot having circumferentially spaced radially extendingstarting and ending edges closely adjacent the radial edges of theimpeller blades, the starting edge being the upstream edge with regardto the rotational direction of the impeller wheel and (g) a covering noelement defining an open pocket adjacent the impeller chamber extendingfrom the upstream edge of the suction slot, said pocket having acooperating surface that cooperates with the fluid that is recirculatedby the impeller wheel and redirects the same back into the radialleading edges of the blades.

2. A pump as claimed in claim 1, wherein said surface is inclined towardthe impeller Wheel in the direction of the ending edge of the suctionslot and is spaced a substantially small distance from the leading edgesof the blades.

References Cited by the Examiner UNITED STATES PATENTS 1,969,881 8/1934Gardner 103--96 SAMUEL LEVINE, Primary Examiner.

HENRY F. RADUAZO, Examiner.

1. A SELF-PRIMING SIDE CHANNEL CENTRIFUGAL PUMP COMPRISING: (A) A CASINGDEFINING A SUCTION CHAMBER AND AN IMPELLER CHAMBER; (B) A SHAFTJOURNALLED FOR ROTATION IN THE CASING; (C) AN IMPELLER WHEEL FIXED ONSAID SHAFT AND DISPOSED IN THE IMPELLER CHAMBER FOR ROTATION THEREIN ANDHAVING RADIAL BLADES; (D) A PARTITION IN SAID CASING AND SEPARATING SAIDSUCTION CHAMBER AND SAID IMPELLER CHAMBER; (E) SAID BLADES BEINGRADIALLY DISPOSED IN SAID IMPELLER CHAMBER AND HAVING RADIAL LEADINGEDGES FACING SAID SUCTION CHAMBER; (F) SAID PARTITION BEING PROVIDEDWITH A SUCTION SLOT COMMUNICATING SAID CHAMBERS, SAID SLOT HAVINGCIRCUMFERENTIALLY SPACED RADIALLY EXTENDING STARTING AND ENDING EDGESCLOSELY ADJACENT THE RADIAL EDGES OF THE IMPELLER BLADES, THE STARTINGEDGE BEING THE UPSTREAM EDGE WITH REGARD TO THE ROTATIONAL DIRECTION OFTHE IMPELLER WHEEL AND (G) A COVERING RIB ELEMENT DEFINING AN OPENPOCKET ADJACENT THE IMPELLER CHAMBER EXTENDING FROM THE UPSTREAM EDGE OFTHE SUCTION SLOT, SAID POCKET HAVING A COOPERATING SURFACE THATCOOPERATES WITH THE FLUID THAT IS RECIRCULATED BY THE IMPELLER WHEEL ANDREDIRECTS THE SAME BACK INTO THE RADIAL HEADING EDGES OF THE BLADES.